A 3rd party developed an EA to run on MT4. However i now want to run it 9n MT5.

They have quoted me a price of $90 to make this conversion.

Does this sound reasonable?

Allso - who owns the source code? I paid them $100 do develop the original EA.

*If i own i thenm presumably i could send it to someone3 else to do it cheaper)

If you paid $100 for the original EA, then a conversion can be just as time-consuming, so $90 is reasonable!

If you received the source code (.mq4) file(s), then yes, you could have someone else convert it. However, if you only agreed to receive an executable (.ex4), then you will not be able to so.

When hiring someone to code something for you, make sure that the agreement includes you receiving the full source code as well. This is the safest way to guarantee you the freedom to be able to make future changes by another party.